There was a large contingent of New England Patriots sitting courtside, including tight end Rob Gronkowski, backup quarterback Jimmy Garoppolo and owner Robert Kraft.
As a team the Cavs were 19 of 39 from the 3-point line.
Cleveland now holds a 2-0 series lead over Boston.
Isaiah Thomas sat out the second half of Boston's embarrassing Game 2 loss to the Cavaliers, and it's unclear if he'll be able to suit up in Sunday's Game 3 in Cleveland.
Kevin Love has also been almost unstoppable at times.
Starting late in the first quarter with a driving layup from Irving, the Cavaliers went on a 23-4 scoring run over a six-plus minute stretch and staked themselves out to a 53-22 lead over the Celtics with 6:15 to play in the first half.
James, who was a plus-46 in the game (plus-63 in two games), dished out seven assists and added four rebounds, four steals and three blocked shots. Love posted 21 points with 12 rebounds in just 27 minutes of action. They entered halftime with the same amount of turnovers as made field goals (11); and just 32 points, which was only two more than the Cavaliers tallied from the 3-point arc alone.
Isaiah Thomas missed the second half with a strained right hip, but his absence had no say in this game. Rookie Jaylen Brown led the Celtics with 19 points off the bench.
The Cavs won their 13th consecutive playoff game dating to last season, tying the Los Angeles Lakers from 1988 and 1989 for the all-time record.
The Cavaliers did their damage in the first two games of this series on the road. The defending National Basketball Association champions are firing on all cylinders, moving to 10-0 this postseason. Cavs coach Tyronn Lue called it a "smart?"
"This team has fight".
But against the Celtics, you would think they had a team of Kawhi Leonards or something the way they absolutely stone-walled Boston at every turn. "As well as we played tonight, we've got a couple of things we can do better".
"We're not scared of Cleveland". "They're not the Monstars". They could use more physicality to slow down James.
He might have changed his mind by midway through the second quarter. The Orlando Magic beat them by 47 points in the first round of the 1995 postseason. That statistic was erased Friday when the Cavs opened a 72-31 margin after 24 minutes.
The 41-point bulge through two quarters accounted for the largest halftime lead in National Basketball Association postseason history, besting the 40-point cushion the Detroit Pistons held over the Washington Bullets in Game 2 of their 1987 first-round series (Detroit led 76-36).
Celtics coach Brad Stevens said after the game that Thomas' injury is something he's been dealing with for a bit.
The Cavaliers struggled from three-point range early in Game 1, but that was far from the case from the start of Game 2.
"But today I thought he looked much different in the first half".
"That was not our concern going into the second half", said LeBron James, who led all scorers with 30 points. But that was just the beginning of the Celtics' unraveling.
As complimentary as Stevens was of the Cavs after the series opener, he didn't believe a defeatist attitude would creep into the Celtics' minds.
"He was pretty despondent not to be able to play", Stevens said". "We're going back home, we're not going to get comfortable".
"We've been built in a way of having a chip on your shoulder, competing".
"I hope not", he said.